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Peer Reviewed
See detailRandom distribution of iron among the two binding sites of transferrin in patients with various hematologic disorders.
Beguin, Yves ULg; Huebers, H.; Finch, C. A.

in Clinica Chimica Acta (1988), 173(3), 299-304

The distribution of iron among the two binding sites of transferrin was studied by isoelectric focusing in 41 patients with a variety of disorders of iron metabolism and erythropoiesis. The proportion of ... [more ▼]

The distribution of iron among the two binding sites of transferrin was studied by isoelectric focusing in 41 patients with a variety of disorders of iron metabolism and erythropoiesis. The proportion of diferric and the two monoferric transferrins were very close to the values predicted from the transferring saturation. It is concluded that iron distribution on transferrin is random or close to random within the experimental error in patients with a variety of clinical disorders. [less ▲]

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See detailRandom generation of dichotomous CAT response patterns with the R package catR
Magis, David ULg

Conference (2013, February 14)

The purpose of this talk is to briefly introduce the R package catR that permits random generation of response patterns under a computerized adaptive testing (CAT) framework. First, an outline of the CAT ... [more ▼]

The purpose of this talk is to briefly introduce the R package catR that permits random generation of response patterns under a computerized adaptive testing (CAT) framework. First, an outline of the CAT is proposed, with emphasis on the main concepts (item bank, ability estimation, next item selection, stopping rule, item exposure and content balancing). Then, the performance of the catR package is described by making connections between the general CAT framework and the functionalities of the R functions within catR. An example will be displayed, either as a “live” demonstration of catR or as part of the talk. Potential extensions of catR will also be discussed. The catR package was jointly developed by Gilles Raîche (Université du Québec à Montréal, Canada). [less ▲]

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See detailRandom generation of response patterns under computerized adaptive testing with the R package catR
Magis, David ULg; Raîche, Gilles

in Journal of Statistical Software (2012), 48

This paper outlines a computerized adaptive testing (CAT) framework and presents an R package for the simulation of response patterns under CAT procedures. This package, called catR, requires a bank of ... [more ▼]

This paper outlines a computerized adaptive testing (CAT) framework and presents an R package for the simulation of response patterns under CAT procedures. This package, called catR, requires a bank of items, previously calibrated according to the four-parameter logistic (4PL) model or any simpler logistic model. The package proposes several methods to select the early test items, several methods for next item selection, di erent estimators of ability (maximum likelihood, Bayes modal, expected a posteriori, weighted likelihood), and three stopping rules (based on the test length, the precision of ability estimates or the classi cation of the examinee). After a short description of the di erent steps of a CAT process, the commands and options of the catR package are presented and practically illustrated. [less ▲]

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See detailRandom Handshaking and Information Recovery Between Scales and Models
Ghanem, Roger; Arnst, Maarten ULg; Phipps, Eric et al

Conference (2011, July 05)

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See detailRandom matrix model for antiferromagnetism and superconductivity on a two-dimensional lattice
Vanderheyden, Benoît ULg; Jackson, A. D.

in Physical Review B (Condensed Matter and Materials Physics) (2009), 79(14), 144502

We suggest a new mean-field method for studying the thermodynamic competition between magnetic and superconducting phases in a two-dimensional square lattice. A partition function is constructed by ... [more ▼]

We suggest a new mean-field method for studying the thermodynamic competition between magnetic and superconducting phases in a two-dimensional square lattice. A partition function is constructed by writing microscopic interactions that describe the exchange of density and spin fluctuations. A block structure dictated by spin, time-reversal, and bipartite symmetries is imposed on the single-particle Hamiltonian. The detailed dynamics of the interactions are neglected and replaced by a normal distribution of random matrix elements. The resulting partition function can be calculated exactly. The thermodynamic potential has a structure which depends only on the spectrum of quasiparticles propagating in fixed condensation fields, with coupling constants that can be related directly to the variances of the microscopic processes. The resulting phase diagram reveals a fixed number of phase topologies whose realizations depend on a single coupling parameter ratio, alpha. Most phase topologies are realized for a broad range of values of alpha and can thus be considered robust with respect to moderate variations in the detailed description of the underlying interactions. [less ▲]

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See detailRandom matrix model for chiral symmetry breaking and color superconductivity in QCD at finite density
Vanderheyden, Benoît ULg; Jackson, A. D.

in Physical Review. D : Particles and Fields (2000), 62(9), 094010

We consider a random matrix model which describes the competition between chiral symmetry breaking and the formation of quark Cooper pairs in QCD at finite density. We study the evolution of the phase ... [more ▼]

We consider a random matrix model which describes the competition between chiral symmetry breaking and the formation of quark Cooper pairs in QCD at finite density. We study the evolution of the phase structure in temperature and chemical potential with variations of the strength of the interaction in the quark-quark channel and demonstrate that the phase diagram can realize a total of six different topologies. A vector interaction representing single-gluon exchange reproduces a topology commonly encountered in previous QCD models, in which a low-density chiral broken phase is separated from a high-density diquark phase by a first-order line. The other five topologies either do not possess a diquark phase or display a new phase and new critical points. Since these five cases require large variations of the coupling constants away from the values expected for a vector interaction, we conclude that the phase diagram of finite density QCD has the topology suggested by single-gluon exchange and that this topology is robust. [less ▲]

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See detailA random matrix model for color superconductivity at zero chemical potential
Vanderheyden, Benoît ULg; Jackson, A. D.

in Physical Review. D : Particles and Fields (2000), 61(7), 076004

We discuss random matrix models for the spontaneous breaking of both chiral and color symmetries at zero chemical potential and finite temperature. Exploring different Lorentz and gauge symmetric color ... [more ▼]

We discuss random matrix models for the spontaneous breaking of both chiral and color symmetries at zero chemical potential and finite temperature. Exploring different Lorentz and gauge symmetric color structures of the random matrix interactions, we find that spontaneous chiral symmetry breaking is always thermodynamically preferred over diquark condensation. Stable diquark condensates appear only as SU(2) rotated chiral condensates, which do not represent an independent thermodynamic phase. Our analysis is based on general symmetry arguments and hence suggests that no stable and independent diquark phase can form in QCD with two flavors at zero quark chemical potential. [less ▲]

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See detailRandom matrix models for chiral and diquark condensation
Vanderheyden, Benoît ULg; Jackson, A. D.; Lansberg, Jean-Philippe ULg et al

in AIP Conference Proceedings (2005), 775

We consider random matrix models for the thermodynamic competition between chiral symmetry breaking and diquark condensation in QCD at finite temperature and finite baryon density. The models produce mean ... [more ▼]

We consider random matrix models for the thermodynamic competition between chiral symmetry breaking and diquark condensation in QCD at finite temperature and finite baryon density. The models produce mean field phase diagrams whose topology depends solely on the global symmetries of the theory. We discuss the block structure of the interactions that is imposed by chiral, spin, and color degrees of freedom and comment on the treatment of density and temperature effects. Extension of the coupling parameters to a larger class of theories allows us to investigate the robustness of the phase topology with respect to variations in the dynamics of the interactions. We briefly study the phase structure as a function of coupling parameters and the number of colors. [less ▲]

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See detailRandom matrix models for phase diagrams
Vanderheyden, Benoît ULg; Jackson, A. D.

in Reports on Progress in Physics (2011), 74

We describe a random matrix approach that can provide generic and readily soluble mean-field descriptions of the phase diagram for a variety of systems ranging from QCD to high-T_c materials. Instead of ... [more ▼]

We describe a random matrix approach that can provide generic and readily soluble mean-field descriptions of the phase diagram for a variety of systems ranging from QCD to high-T_c materials. Instead of working from specific models, phase diagrams are constructed by averaging over the ensemble of theories that possesses the relevant symmetries of the problem. Although approximate in nature, this approach has a number of advantages. First, it can be useful in distinguishing generic features from model-dependent details. Second, it can help in understanding the `minimal' number of symmetry constraints required to reproduce specific phase structures. Third, the robustness of predictions can be checked with respect to variations in the detailed description of the interactions. Finally, near critical points, random matrix models bear strong similarities to Ginsburg-Landau theories with the advantage of additional constraints inherited from the symmetries of the underlying interaction. These constraints can be helpful in ruling out certain topologies in the phase diagram. In this Key Issue, we illustrate the basic structure of random matrix models, discuss their strengths and weaknesses, and consider the kinds of system to which they can be applied. [less ▲]

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See detailRandom matrix study of the phase structure of QCD with two colors
Vanderheyden, Benoît ULg; Jackson, A. D.

in Physical Review. D : Particles and Fields (2001), 64(7), 074016

We apply a random matrix model to the study of the phase diagram of QCD with two colors, two flavors, and a small quark mass. Although the effects of temperature are only included schematically, this ... [more ▼]

We apply a random matrix model to the study of the phase diagram of QCD with two colors, two flavors, and a small quark mass. Although the effects of temperature are only included schematically, this model reproduces most of the ground state predictions of chiral perturbation theory and also gives a qualitative picture of the phase diagram at all temperatures. It leads, however, to an unphysical behavior of the chiral order parameter and the baryon density in vacuum and does not support diquark condensation at arbitrarily high densities. A better treatment of temperature dependence leads to correct vacuum and small temperature properties. We compare our results at both high and low densities with the results of microscopic calculations using the Nambu-Jona-Lasinio (NJL) model and discuss the effects of large momentum scales on the variations of condensation fields with chemical potential. [less ▲]

Detailed reference viewed: 29 (12 ULg)
See detailRandom Response Model for estimating illicit drug prevalence among youth. A feasibility study.
Mauer, M.; Donneau, Anne-Françoise ULg; Pasquasy, N. et al

Report (2003)

Detailed reference viewed: 16 (3 ULg)
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See detailRandom subwindows and extremely randomized trees for image classification in cell biology
Marée, Raphaël ULg; Geurts, Pierre ULg; Wehenkel, Louis ULg

in BMC Cell Biology (2007), 8(Suppl. 1),

Background: With the improvements in biosensors and high-throughput image acquisition technologies, life science laboratories are able to perform an increasing number of experiments that involve the ... [more ▼]

Background: With the improvements in biosensors and high-throughput image acquisition technologies, life science laboratories are able to perform an increasing number of experiments that involve the generation of a large amount of images at different imaging modalities/scales. It stresses the need for computer vision methods that automate image classification tasks. Results: We illustrate the potential of our image classification method in cell biology by evaluating it on four datasets of images related to protein distributions or subcellular localizations, and red-blood cell shapes. Accuracy results are quite good without any specific pre-processing neither domain knowledge incorporation. The method is implemented in Java and available upon request for evaluation and research purpose. Conclusion: Our method is directly applicable to any image classification problems. We foresee the use of this automatic approach as a baseline method and first try on various biological image classification problems. [less ▲]

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See detailRandom Subwindows and Multiple Output Decision Trees for Generic Image Annotation
Dumont, Marie; Marée, Raphaël ULg; Geurts, Pierre ULg et al

Poster (2007)

Detailed reference viewed: 42 (7 ULg)
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See detailRandom Subwindows and Randomized Trees for Image Retrieval, Classification, and Annotation
Marée, Raphaël ULg; Dumont, Marie; Geurts, Pierre ULg et al

Poster (2007, July 22)

Detailed reference viewed: 36 (4 ULg)
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See detailRandom Subwindows for Robust Image Classification
Marée, Raphaël ULg; Geurts, Pierre ULg; Piater, Justus ULg et al

in Proceedings of the IEEE International Conference on Computer Vision and Pattern Recognition (CVPR 2005) (2005)

We present a novel, generic image classification method based on a recent machine learning algorithm (ensembles of extremely randomized decision trees). Images are classified using randomly extracted ... [more ▼]

We present a novel, generic image classification method based on a recent machine learning algorithm (ensembles of extremely randomized decision trees). Images are classified using randomly extracted subwindows that are suitably normalized to yield robustness to certain image transformations. Our method is evaluated on four very different, publicly available datasets (COIL-100, ZuBuD, ETH-80, WANG). Our results show that our automatic approach is generic and robust to illumination, scale, and viewpoint changes. An extension of the method is proposed to improve its robustness with respect to rotation changes. [less ▲]

Detailed reference viewed: 61 (7 ULg)
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See detailRandom-incidence scattering coefficients of infinite sine-shaped surfaces
Embrechts, Jean-Jacques ULg

in Proceedings of the 4th Forum Acusticum Congress (2005)

Detailed reference viewed: 16 (8 ULg)